The present invention relates to a drainage preference operating method which can prevent stop of drain pumps as far as possible and enables a draining pump plant to fulfill its function maximally even when any component equipment of the draining pump plant breaks down, and a draining pump system which implements the operating method.
A draining pump system such as for use in draining pump plants serves to collect water drained off from urban districts, introduce the water into an influent tank, and pump out the water, flowing into the influent tank, to rivers or other watercourses by using a plurality of drain pumps. The draining pump system is comprised of prime movers for driving respective drain pumps, and a group of auxiliaries for supplying fuel, lubricating oil, cooling water, air, etc. to the drain pumps and the prime movers. Because this type draining pump system is generally intended to prevent drainage areas from being flooded, there is a demand to continuously operate the drain pumps as far as possible under a condition of large influent amount even if the pumps are found failed.
As a step to be taken in the even of such a failure, conventional draining pump plants has been designed to divide failures into two categories, i.e., minor and m for failures, as disclosed in Japanese Patent Laid-Open No. 1-294992, for example. More specifically, failures of the type that can be judged as not leading to damages of the equipment for some time to come are grouped as minor ones. In this case, only an buzzer alarm is effected and operation of the relevant drain pump is continued. On the other hand, failures of the type that can be judged as leading to damages of the equipment in a short time are grouped as major ones. In this case, not only an buzzer alarm is effected, but also operation of the relevant drain pump is brought into emergent stop.
For the purpose of earlier restoration from failures, it has also been practiced to install a failure diagnosis device for pursuing the failure cause, or a failure adaptive guidance device for expediting the restoration from failures. One of this type devices is described in, by way of example, "Pump Plant Failure Diagnosis System", Mitsubishi Heavy Industries Technical Report, Vol. 26, No. 2 (March 1989).
In practice, however, judgment on a degree of necessity for operating individual drain pumps and the presence or absence of past operation record under a failed condition is still made only relying upon experiences and perception of an operator. This means that emergent operation of failed drain pumps is performed without definite judgment standards.
Further, the technique of checking the interior of equipment by fiber scopes or judging a normality level of equipment based on analysis of vibrations during the operation has been improved recently. This type technique is however employed just in judging the need of repair.
In the prior art stated above, a degree of failure is evaluated using reference values for failure judgment which are fixedly determined and whether to continue or stop operation of a drain pump is judged on the basis of the evaluation result, taking into account neither the operating state of the drain pump nor a tendency in changes of the failed condition until reaching the reference values for failure judgment. Accordingly, there has suffered from the problem that the drain pump may be stopped even in no need of stopping it in its actual state, thus disabling of cover the amount of water required to be pumped out, or that any equipment may be damaged with undue continuation of the operation.